Key Performance Characteristics

 
SHS 7172 PTAW weld overlay for hardfacing applications feature high resistance to abrasion while maintaining very high toughness. SHS 7172 forms a matrix consisting of spherical α-Fe dendrites interdispersed with complex borocarbide phases which results in a microstructure which has superior combinations of hardness and toughness. Cost is an additional benefit of SHS 7172 since it is a stand-alone PTAW powder that provides superior properties without incorporating high cost tungsten-carbide hardmetal phases or volatile elements such as nickel.

High Hardness and Abrasion Resistance
Rockwell C (HRc) hardness measurements show that SHS 7172 weld deposits develop a microstructure which yields high HRc hardness from 64 - 66. Due to this high hardness, SHS 7172 weld overlays exhibit high resistance to abrasion with uniform wear rates throughout the volume due to the uniformly fine sized microstructure. Abrasion resistance can be reduced in half by applying two or more passes.

Weld Overlay Toughness
The toughness of SHS 7172 welds has been measured using both Palmqvist indentation techniques and impact testing using a drop tower. Palmqvist measurements were done at very high loads from 150 to 400 kg, which are necessary to initiate cracking. Measurements show that the toughness of SHS 7172 weld deposits is very high from 40 to 75 MPam^1/2. Additionally, in drop impact tests conducted up to 165 ft-lbs, SHS 7172 sustained multiple impacts without damage. This extreme toughness is enabled by crack bridging from the spherical ductile dendrites that form in concurrence with the hard borocarbide phases, as indicated in the SEM backscattered electron image to the right. The combination of high hardness, high wear resistance and very high toughness allows SHS 7172 PTAW to excel in demanding service environments where PTAW weld materials generally do not perform well.

Weld Parameters
For SHS 7172 PTAW weld parameters, contact NanoSteel at 1-877-293-NANO or info@nanosteelco.com.